|During your dives on the sites on the east coast, it is possible to come across several species of sharks. Some are frequent and others more rare, but we are never safe from a pleasant surprise.|
Sharks, rays and chimaeras belong to the class of chondrichthyans, ie cartilaginous fish. Only rays and sharks make up the elasmobranch subclass. Their body is covered with scales which are in fact cutaneous denticles giving them perfect velocity in the water. They are also characterized by the presence of 4 to 7 gill slits (5 in the vast majority), reproduce by internal fertilization and are oviparous (lay eggs) or ovoviviparous (oviparous whose eggs hatch in the belly of the female).
There are approximately 440 species of sharks. According to their morphological and anatomical characteristics, they are classified into 8 orders and 35 families. Their sizes are very varied, from the smallest like the dwarf shark (squaliolus laticaudus) and its 17 cm, to the largest the whale shark (rhincodon typus) that can exceed 15 m.
To oxygenate the vast majority of sharks are forced to swim in order to maintain a current of water that circulates through their mouth to the gills. Some to rest on the bottom face the current with their mouths open to reproduce the same phenomenon. Still others have the ability to suck up water and push it out through their gills to meet their oxygen needs, allowing them to stay at the bottom even without current.
Sharks have several rows of teeth that renew regularly. Some sharks lose more than 30,000 teeth in their lifetime.
The shark was one of the very first jawed vertebrates and has remained virtually unchanged since its appearance 400,000 million years ago. It has shaped our oceans, influencing the behavior of different species of fish.
They are present in all oceans, warm tropical waters, temperate seas and polar seas, near the surface, but also at depths of hundreds of meters, near the coast, or in the open sea .
In French Polynesia, 19 species of sharks have been recorded to date, some are very easily observed such as the blacktip shark, particularly in the Tuamotu archipelago, and others almost never observed, such as the ferocious Squalalet which lives in depth during the day.
Check out some species below.
|BLACKTIP SHARK carcharhinus melanopterus|
The blacktip shark frequents the shallow waters of coral reefs. In Polynesia you can easily observe it along the beaches in a few tens of centimeters of water, the dorsal fin sticking out of the water. It has a brownish gray coat, a white belly, the muzzle is short and rounded and the tips of all the fins are black. A white spot appears under the black apex of the 1st dorsal fin. This small shark measures between 0.80 cm and 130 cm. The blacktip shark feeds mainly on fish, but also on crustaceans, cephalopods and other molluscs.
|LAGOON WHITETIP SHARK triaenodon obesus|
The silhouette of triaenodon obesus is slender and very elongated, it measures between 120 cm and 170 cm
Its back is gray punctuated with black spots and its belly is whitish. The ends of its dorsal fins are white. It is observed during the day, often resting on the bottom facing the current and becomes very active at night. A nocturnal hunter, it feeds on small fish and invertebrates (crustaceans and cephalopods) which it skilfully unearths in the coral reef.
|GRAY REEF SHARK carcharhinus amblyrhynchos|
It is a medium-sized shark with a moderately long, broadly rounded snout. Its caudal fin is edged in black. The coat is bronze-grey and the belly whitish. With the exception of the 1st dorsal, the other fins on their posterior part draw on the black. He measures between 120 cm and 180 cm.
It frequents the outer slopes, passes and approaches to coral reefs, sometimes lagoons. This shark is present between the surface and 280 m depth. It likes areas close to strong currents. This sedentary predator feeds mainly on medium-sized reef fish (40cm) and also cephalopods and crustaceans.
It gathers in shoals of several hundred individuals, especially in certain passes in the Tuamotu.
|GREAT HAMMERHEAD SHARK sphyrna mokarran|
There are 9 different species of hammerhead sharks, the sphyrna mokarran is the largest of them, being able to exceed 5.50 m even if individuals of 3 m are more frequent.
Its eyes are located at the ends of the hammer-shaped head, the almost straight anterior edge of which is slightly serrated. This atypical head shape gives it even greater sensitivity to electric and electromagnetic fields.
Its back is gray brown and its belly is white. Its body is massive with a very high and concave first dorsal fin at the back, the second dorsal is short, the pelvic is also concave at the back and the caudal has very pointed lobes with the upper part very developed.
This pelagic shark migrates in schools or sometimes remains sedentary near coastal areas. Adults tend to be solitary. Their binocular sight allows them to precisely attack their prey. They feed mainly on fish such as rays. They also consume squid, octopus, crustaceans and occasionally other sharks, including those of their species.
On the Tahiti peninsula, it is regularly observed on the surface, the easily recognizable dorsal fin sticking out of the water.
|Scalloped Hammerhead Shark sphyrna lewini|
This hammerhead shark also called scalloped hammerhead is smaller than the mokarran, it usually measures between 2 and 3 m. It has a large flattened and arched head in the shape of a scallop. The middle of the head is marked by a characteristic deep notch. The pectoral fins are small and their lower ends are black. The first dorsal fin is large and triangular. The second dorsal is characterized by a free lobe and a marked concave upper edge. Its coat is greyish and its belly white. The scalloped hammerhead shark is a very active hunter. It feeds on fish, cephalopods, rays and sharks.
Like the great hammerhead shark, the scalloped hammerhead is regularly seen at the peninsula moving just below the surface.
|OCEANIC WHITE TIP SHARK carcharhinus longimanus|
The parata (Tahitian name) is very easily recognizable by its large rounded pectoral fins with white tips. Its color varies from gray brown on the back to white on the belly. Its dorsal, pectoral and caudal fins are marked with mwhite arbors.
Most specimens are around 2 m, but a few rare individuals can reach 2.50 to 3 m, the largest specimen observed was 4 m. Opportunistic and inquisitive by nature, the Longimanus feeds on all bony (tuna, barracuda, marlin...) or cartilaginous (rays, other sharks) oceanic fish, squid, sea turtles, seabirds, marine mammals but also carrion and detritus (cetacean carcasses).
It is a difficult shark to meet since it lives offshore and the species has been seriously victimized by fishing. It is sometimes found near groups of pilot whales.
|SILKY SHARK carcharhinus falciformis|
The silky shark is an oceanic species with a slender, slender body, the largest individuals can reach a size of over 3 meters. It is recognizable by its pointed snout and its short, rounded 1st dorsal fin.
It is a tropical migratory species that is found all over the planet, in coastal seas and in the open sea, at depths of up to 500 meters. It can be found at the exit of passes in open water. It feeds on all bony oceanic fish (tuna, barracuda, marlin, etc.) or cartilaginous (rays, other sharks), squid.
This shark, like many offshore species, has an inquisitive and curious character. He does not hesitate to come and meet any organism or object he encounters.
|TIGER SHARK galeocerdo cuvier|
|WHALE SHARK rhincodon typus|